Various attempts have been made to control weeds and other unwanted growth which occurs in furrows between the dikes used for the growing of vegetables and fruits. These dikes usually are covered in plastic to limit the amount of unwanted growth on the dikes. The crops at the top of the dikes pass through slits in the plastic. The furrows between adjacent dikes are used for irrigation purposes and travel of farm equipment. Unwanted weeds grow in the furrows which compete with the food product for the nutrients and water contained in the soil.
In U.S. Pat. No. 3,581,993 to Reams, a foldable agricultural spray boom incorporates a hydraulic cylinder which causes the boom to unfold when actuated by the pressurized spray liquid. In the unfolded position, a valve establishes a fluid path through the cylinder to the boom spray nozzles.
U.S. Pat. No. 1,462,861 to Jordan and U.S. Pat. No. 4,353,505 to Kinder disclose crop sprayers with skirts to limit the spray or dust to a row of planted crops. The Kinder patent also discloses a drift-free spraying apparatus adapted for movement in connection with a vehicle and includes a spray bar mounted within a bottomless, rectangular, box-type housing in communication with a fluid pump and reservoir assembly, adapted for emitting fluid in a mist configuration upon the surface to be sprayed through nozzles provided in the spray bar.
U.S. Pat. No. 3,445,961 to Elsworth, U.S. Pat. No. 3,977,605 to Sheldon, U.S. Pat. No. 4,350,294 to Gaspard, and U.S. Pat. No. 4,736,888 to Fasnacht disclose herbicide sprayers for use in planted fields. These patents include various means for protecting the crops, either by carefully limiting the spread of the herbicide spray or by shielding the crops from the spray. In the Gaspard patent, spray nozzles are disclosed as being mounted on pivoting arms including a skid which runs along a furrow. This keeps the nozzle at a constant height and allows control of the spread of the herbicide without lateral control.